Control devices for landing gear and hatchdoors with mechanical-hydraulic sequences

ABSTRACT

A control device for the retractable undercarriage of aircraft and for the hatchdoors of the housing of the retracted undercarriage with their actuating and locking members and control members for supplying them in mechano-hydraulic sequential stages from a general lifting conduit and a general lowering conduit for the undercarriage, comprising a jack actuating said hatchdoors, a slide valve distributor supplying said jack, and a kinematic coupling mechanically operated by the undercarriage and placing said slide valve in three characteristic positions: -A FIRST POSITION OPERATED BY THE UNDERCARRIAGE IN ITS LOCKED DOWN POSITION, IN WHICH SAID DISTRIBUTOR CONNECTS THE GENERAL LOWERING CONDUIT TO THE CHAMBER OF SAID JACK ACTUATING THE CLOSURE OF SAID HATCHDOORS, AND THE GENERAL LIFTING CONDUIT TO THE CHAMBER OF SAID JACK ACTUATING THE OPENING OF SAID HATCHDOORS; -A SECOND POSITION OPERATED BY THE UNDERCARRIAGE IN THE UNLOCKED POSITION, IN WHICH SAID DISTRIBUTOR ACTS, THROUGH THE INTERMEDIARY OF PASSAGES OF REDUCED SECTION AND SPRING CONTROLLED VALVES, TO CONNECT THAT OF THE TWO GENERAL LOWERING AND LIFTING CONDUITS WHICH IS UNDER PRESSURE TO THE CHAMBER OF THE JACK ACTUATING THE OPENING OF SAID HATCHDOORS, AND THE OTHER OF SAID TWO GENERAL CONDUITS TO THE CHAMBER OF THE JACK ACTUATING THE CLOSURE OF SAID HATCHDOORS; -A THIRD POSITION OPERATED BY THE UNDERCARRIAGE IN ITS LOCKED RETRACTED POSITION IN WHICH THE DISTRIBUTOR CONNECTS SAID GENERAL LIFTING CONDUIT TO THE CHAMBERS OF SAID JACK ACTUATING THE CLOSURE OF SAID HATCHDOORS, AND SAID GENERAL LOWERING CONDUIT TO THE CHAMBER OF SAID JACK ACTUATING THE OPENING OF SAID HATCHDOORS.

llnite [l5] 3,652fi39 Lucien 5] ar. 2, R972 [54] CONTRUL DEVICES FOR LANDING and for the hatchdoors of the housing of the retracted un- GEAR AND HATCH-[DOORS WITH dercarriage with their actuating and locking members and MECHANHCAL HYDRAULIC control members for supplying them in mechano-hydraulic SEQUENCES sequential stages from a general lifting conduit and a general lowering conduit for the undercarriage, comprising a jack ac- [72] Inventor: Ren Lu ien, 56 B l d M ill tuating said hatchdoors,aslide valve distributor supplying said Neuilly-sur-Seine, Fran e jack, and a kinematic coupling mechanically operated by the undercarriage and placing said slide valve in three charac- [22] Flled' 1970 teristic positions: [21] Appl' 12526 a first position operated by the undercarriage in its locked down position, in which said distributor connects [30] Foreign Application Priority Data the general lowering conduit to the chamber of said jack eagre Closure f F9? ,ha hsha t nd the se f t. Jan 1969 France "6902189 lifting conduit to the chamber of said jack actuating the 52 U.S.Cl. ..244/102 A, l37/625.69 Opemng of lwftchdwsi [51] lnt.Cl ..B64c 25/16 a Second posmon operated by the undercamage m the 58 Field of Search ..244/102R 102 A 137/625 69 unlocked positim in which Said acts hmugh the intermediary of passages of reduced section and spring [56] References Cited controlled valves, to connect that of the two general lowering and lifting conduits which is under pressure to the cham- UNITED STATES PATENTS ber of the jack actuating the opening of said hatchdoors, and the other of said two general conduits to the chamber of IBl'Wll'i the j actuating the closure of Said hatchdoors; 3263574 41966 2322? -a third position operated by the undercarriage in its Primary Examiner-Milton Buchler Assistant Examiner-Paul E. Sauberer Attorney-Walters, Roditi, Schwartz & Nissen [5 7] ABSTRACT locked retracted position in which the distributor connects said general lifting conduit to the chambers of said jack actuating the closure of said hatchdoors, and said general lowering conduit to the chamber of said jack actuating the opening of said hatchdoors.

A control device for the retractable undercarriage of aircraft 3 Claims, 8 Drawing Figures 0 I 0 I l O Q 24 g l a 4 CONTROL DEVICES FOR LANDING GEAR AND HATCll-IDOORS WITH MECHANICAL-HYDRAULIC SlEQUENCES The invention relates to landing gears and undercarriages for aircraft, and more precisely to retractable wheels and the doors of their housings.

Mechanical-hydraulic devices are known which are employed for operating undercarriages and the corresponding trapdoors, and which permit the door to be closed automatically when the undercarriage is up or down.

More precisely, devices are known which carry out the movements of the undercarriage and the hatchdoor in a predetermined order, by which the doors are kept open, during the operation of the landing gear, solely by a hydraulic lock. This system has the drawback of defining a door-position as a function of a fluid-tightness condition, with a possible breakaway in the event of a leakage.

The object of the invention is to eliminate this disadvantage.

According to the invention, in the doors-open position, the chamber producing this opening of the jack is in communication with the source of pressure, and the hydraulic lock, although existing, only serves if there is a momentary fall in pressure at the source.

In the device according to the invention, the distributor which controls the supply to the hatchdoor jack is actuated mechanically by the landing gear and effects this supply in two sequential stages.

The first sequence which takes place in the presence of the hydraulic order to lower the undercarriage, supplies the jack:

- in the opening direction when the undercarriage is locked in the retracted position;

- in the opening direction but at reduced power when the undercarriage is not locked;

- in the closure direction when the undercarriage is locked in the down position.-

The second sequence, which takes place in the presence of the hydraulic order to raise the wheels actuates the jack:

- in the opening direction when the undercarriage is locked in the down position;

- in the opening direction with reduced power when the undercarriage is not locked;

- in the closure direction when the undercarriage is locked in the retracted position.

It will be observed that in both the above sequences, when the undercarriage is not locked, the jack is positively actuated towards opening, but under reduced power, i.e. with throttling and spring clapper-valves, which, in the event of a fall in the pressure from the source, establish the hydraulic lock holding the hatchdoor open.

Briefly, in the device according to the invention, the slide valve of the hatchdoor distributor is mechanically placed, by the undercarriage, in three characteristic positions:

- in the first characteristic position, corresponding to the locked-down position of the undercarriage, the distributor causes the lowering conduit to communicate, by wide passages, with the chamber acting towards closure of the hatchdoor jack, and the lifting conduit with the chamber acting towards opening;

- in the second characteristic position, which corresponds to the unlocked position of the undercarriage, the distributor causes that of the two lifting and lowering conduits which is under pressure to communicate, through restricted passages and spring clapper valves, with the chamber acting towards closure;

- in the third characteristic position, which corresponds to the undercarriage locked in the retracted position, the distributor causes the lifting conduit to communicate, through wide passages, with the chamber acting towards closure, and the lowering conduit with the chamber acting towards opening.

It will be noted that the device according to the invention enables the outward speed of the jack rod to be reduced at the end of opening of the hatchdoor, without the addition of a dash-pot.

In addition, the device according to the invention is characterized, as compared with known arrangements, by its great simplicity, and by the operation of the various distributors by the soleaction of the mechanical coupling between the various elements.

The invention will now be described with reference to the accompanying drawings, given by way of example only and without any limitation. In these drawings:

FIG. 1 shows diagrammatically an application of the invention to an undercarriage with a leg and strut, shown in the down position;

FIG. 2 is a detail showing diagrammatically a coupling between a certain roller and a certain crank-arm of F IG. 1;

FIG. 3 is a detail showing the positions of the hatchdoor distributor of FIG. ll;

FIGS. 4, 5 and 6 are three drawings explaining the operation of the hatchdoor distributor of FIG. 1;

FIGS. 7 and ii are two drawings explaining the operation of the undercarriage distributor of FIG. 1.

The description which follows refers, by way of non-limitative example, to a landing gear comprising mainly a leg, an articulated strut and a jack. It should be noted that the invention is applicable to all undercarriages with retractable wheels.

With reference to FIG. 1, this figure shows an application of the invention to a landing gear, shown in the down position, constituted by a leg 1, actuated by a jack 2 acting between the top of the leg 1 and a strut comprising a lower arm 3 and an upper arm 1, with a jack 11 for releasing the undercarriage in the retractable position, and having a hatchdoor 16, shown in the closed position, with its locking device in the closed position constituted by a hook 17 pivoted on a shaft 21 and restored by a spring 18, a roller 19 pivoted on a fixed shaft 191 and rigidly fixed to a jack 20 comprising a piston 201 restored by a spring 2M.

The device according to the invention comprises mainly a distributor 13 controlling the movements of the undercarriage, a distributor l2 controlling the movements of the hatchdoor, and the operating members of these distributors.

For the undercarriage distributor 13, these members are a cam 14 and crank-rod 15 coupling the cam to the hatchdoor 16. For the hatchdoor distributor 12, these members are the rocking lever 7, one extremity of which is coupled to the locking arm 9 of the hook d, the other to a crank-arm 6 actuated by a cam 5 coupled to the movement of the undercarriage (it is shown keyed on the strut-arm 4, but could be coupled to another element of the undercarriage).

It should be stated that, by an adequate means, the roller 61 mounted on the extremity of the cranlearm 6 is compelled to move on a substantially straight-line trajectory during the angular movement of the leg ll of the undercarriage. Such a means is described below with reference to FIG. 2, which comprises a guide-slot member, shown by way of nonlimitative example. This guiding could be effected by a set of levers (not shown).

Referring now to FIG. 2, a part 22 comprising a slot 221 is fixed. The earn 5 comprising the slot 51 rotates with the strutarm 4 around the point 41. The movement of the roller 61 in the slot 221 can only be made parallel to the sides of the slot.

Thus, the shaft of the upper extremity of the rocking-lever 7 will occupy two characteristic positions due to the profile of the slot $1 of the cam 5 (slope on the portion 53 and then the circular portion 54 having its centre at 41).

With reference to FIG. 3, when the angle a of the leg 0, 71 will occupy the position TB, and when the angle of the leg is greater than a (zone B of FIG. 1) the shaft 71 will take up the position TNB. The shaft 72, which is at the lower portion of the rocking-lever 7 will occupy two characteristic positions, the position CO when the hook is open, the position CF when the hook is closed.

Since in the undercarriage down position the hook 8 of the undercarriage is held open by the spring 10 and the cam is fixed to the hook, and that when the hook is closed the undercarriage cannot be down, the distribution slide-valve (See FIGS. l, 5 and 6) will occupy, taking account of the rocking lever 7 and the crank-arm 73, three characteristic positions (FIG. 3):

TVB undercarriage locked while down;

TNV undercarriage not locked (leg in the angular zone ,8);

THV undercarriage locked while retracted.

The displacement of the shaft 71 from TB to TNB and vice versa is effected by the work supplied by the undercarriage jack 2. The movement of the shaft 72 from C to CF is effected by the work of the jack 24 and the spring 10 while the movement in the opposite direction from CF to CO results from the action of the releasing jack 1 1.

To each of these positions there will correspond a state of the distribution and these conditions will be described later.

There will first be described with reference to FIG. 4 the internal structure of the hatchdoor distributor 12 with a slidevalve 121. The body of this distributor comprises a coupling 122 connected to the lowering conduit and opening into the central bore, on the one hand directly at the extreme left at 123 and at the extreme right at 124, and on the other hand through a conduit 125 of reduced section and a return clapper-valve 126 on the left at 127 and through a conduit 128 of reduced section and an inlet clapper-valve 129 on the right at 1211.

The body of this distributor comprises two passages 1222 and 1223 opening into the central body and coupled respectively to the chambers 232 and 233 of the hatchdoor jack 23. The slide-valve of this distributor is provided with two wide annular grooves 1226 and 1227. The groove 1226 puts the passage 1222 into communication with two of the four openings on the left-hand side and the groove 1227 puts the passage 1223 into communication with two of the four righthand openings as will be explained in detail below.

With reference to FIG. 4, which corresponds to the position TVB of the slide-valve 121, the groove 1226 puts the lowering conduit and the chamber 232 of the hatchdoor jack 23 into communication and the groove 1227 puts the lifting conduit into communication with the chamber 233 of this jack. Thus, when the undercarriage is lowered, the lowering conduit being under pressure and the lifting conduit being on the tank, the chamber 232 is supplied and the chamber 233 is evacuated, the jack 23 actuates the closure of the hatchdoor. Conversely, when the undercarriage is retracted, the lowering conduit being put to the tank and the lifting conduit being under pressure, the chamber 232 is evacuated and the chamber 233 is supplied. The jack actuates the opening of the hatchdoor.

With reference to FIG. 5 which corresponds to the position THV of the slide-valve 121, when the undercarriage is lowered (down circuit under pressure, lifting circuit without pressure), the liquid passes into the distributor 12 through 122, the valve 126 is closed by the pressure, the valve 129 is lifted by the pressure which passes into the groove 1227 after having passed through the conduit 128 of reduced section (the valve 1219 remains closed). The liquid passes out of the distributor by the orifice 1223 and passes into the chamber 233 of the jack 23, tending to push back the piston 231. The liquid expelled from the chamber 232 of the jack passes into the distributor 12 through 1222, passes through the groove 1226 and leaves at 1212, after having lifted the valve 1216 and passed into the conduit 1215 of reduced section. The hatchdoor has a tendency to open.

When the undercarriage is retracted (lowering circuit on the tank, lifting circuit under pressure), the liquid passes into the distributor 12 through 1212, the valve 1216 is closed, the valve 1219 is lifted by the pressure and the liquid passes into the annular groove 1227 after having passed through the conduit 1218 of reduced section (the valve 129 remains closed). The liquid passes out through the orifice 1223; it passes into the chamber 233 of the hatchdoor jack 23 and tends to push back the piston 231. The liquid expelled from the chamber 232 of the jack passes into the distributor at 1222, passes through the annular groove 1226 and leaves at 122 after having lifted the valve 126 (passage through the conduit 125 of reduced section). The hatchdoor has a tendency to open up to abutment for this position of the distributor, whether the undercarriage is being raised or lowered.

With reference to FIG. 6, which corresponds to the position TVH of the slide-valve 121, the groove 1226 puts the lifting conduit into communication with the chamber 232 of the hatchdoor jack 23 and the groove 1227 puts the lowering conduit into communication with the chamber 233 of this jack. Thus, when the undercarriage is lowered, the lowering conduit being under pressure and the lifting conduit being put to the tank, the chamber 233 is supplied and the chamber 232 is evacuated; the jack 23 actuates the opening of the hatchdoor. Conversely, when the undercarriage is raised, the lowering conduit being put to the tank and the lifting conduit being under pressure, the chamber 232 is supplied and the chamber 233 is evacuated; the jack 23 actuates the closure of the hatchdoor.

The distributor 13 which controls the operation of the undercarriage is associated with the movement of the hatchdoor.

The law of movement of the slide-valve 131 of the distributor (FIGS. 7 and 8) is such that the operating jack of the undercarriage is only supplied when the angle of opening of the hatchdoor is sufficient to permit the operation of the undercarriage. Various constructions are of course possible for this purpose; one of these will be described below by way of nonlirnitative example.

With reference to FIG. 7, the coupling between the hatchdoor l6 and the undercarriage distributor 13 is effected by a system comprising a crank-rod 15, a cam 14 with a slot 141 in which circulates a roller 132 fixed on the extremity of the slide-valve 131 by a shaft 133. The cam comprises a circular portion 143 having its center at 142 and a sloping portion 144. It is this portion which acts on the roller 132 at the end of the opening phase. The distributor 13 is a hydraulic double reversing type and will not therefore be described in detail.

When the hatchdoor is closed (position shown) or partly closed (position corresponding to 'y) the slide-valve 131 of the distributor is in the position PF. In this position, whether the pressure is applied or not in the lifting or lowering circuit through the ends 134 or 135, the conduits terminating at the undercarriage jack corresponding to the end-pieces 136 and 137 are put into communication with the return circuit (endpiece 138) and the undercarriage is not actuated.

When the hatchdoor is sufficiently open for the roller to be in the angular zone which corresponds to 6 (FIG. 8) the slide valve of the distributor 13 is in a position such that the communications towards 138 are interrupted, but on the other hand 134 is put into communication with 136, and is put into communication with 137. The undercarriage is lifted or lowered depending on whether the pressure is applied to the lifting or lowering circuit.

What I claim is:

l. A control device for a retractable undercarriage and for the hatchdoor closing its housing, with their actuation and locking devices and control members for supplying said devices in mechanical-hydraulic sequences from a general conduit for lifting the undercarriage and a general conduit for lowering said undercarriage, comprising a jack for actuating said hatchdoor, a slide-valve distributor for supplying said jack and a kinematic coupling actuated mechanically by said undercarriage and placing said slide-valve in three characteristic positions:

a first position controlled by the undercarriage in the lowered position and locked, in which said distributor causes the general lowering conduit to be in communication with the chambers of said jack actuating the closure of said hatchdoor, and said general lifting conduit with the chamber of said jack actuating the opening of said hatchdoor;

a second position, controlled by the undercarriage in the unlocked position, in which said distributor acts, through the intermediary of passages of reduced section and spring clapper-valves, to cause that of said two general lowering and lifting conduits which is under pressure to communicate with the chamber of said jack actuating the opening of said hatchdoor, and the other said general conduit to communicate with the chamber of said jack actuating the closure of said hatchdoor;

third position, controlled by the undercarriage in the retracted and locked position, in which said distributor causes said general lifting conduit to communicate with the chamber of said jack actuating the closure of said hatchdoor, and puts said general lowering conduit into communication with the chamber of said jack actuating the opening of said hatchdoor, said hatchdoor distributor comprising a first coupling connected to the general lifting conduit, a first orifice connected to said first coupling and opening into the bore of said distributor directly at its center, a first channel of reduced section connected to said first coupling, a first return clapper-valve connected to said first channel, a second orifice connected to said first valve and opening into the bore of said distributor on one side of its center, a second channel of reduced section connected to said first coupling, a second inlet clapper-valve connected to said second channel, a third orifice connected to said second valve and opening into the bore of said distributor on the other side of its center, a second coupling connected to said general lowering conduit, a third channel of reduced section connected to said second coupling, a third return clapper-valve connected to said third channel, a fourth orifice connected to said third valve and opening into the bore of said distributor at the side of and beyond said second orifice, a fourth channel of reduced section connected to said second coupling, a fourth inlet clapper-valve connected to said fourth channel, a fifth orifice connected to said fourth valve and opening into the bore of said distributor at the side of and beyond said third orifice, a sixth orifice connected to said second coupling and opening into the bore of said distributor at the side of and beyond said fourth orifice, a seventh orifice connected to said second coupling and opening into the bore of said distributor at the side and beyond said fifth orifice, a third coupling connected to the chamber of said jack actuating the closure of said hatchdoor and opening into the bore of said distributor between said second and fourth orifices, a fourth coupling connected to the chamber of said jack actuating the opening of said hatchdoor and opening into the bore of said distributor between said third and fifth orifices, the slide-valve of said distributor being provided with two annular grooves, a first groove being able to put said second coupling into communication with two contiguous orifices of said first, second, fourth and sixth orifices, a second groove being able to put said fourth coupling into communication with two contiguous orifices of said first, third, fifth and seventh orifices.

2. A device as claimed in claim )1, comprising a jack actuating the undercarriage, a distributor controlled by said hatchdoor and supplying said undercarriage jack only when the opening of said hatchdoor is greater than a predetermined angle, and a cam actuated by said hatchdoor and actuating said undercarriage distributor, said undercarriage distributor connecting the two supply conduits of said undercarriage jack to the general return conduit when the opening of said hatchdoor is less than said predetermined angle or to the general lifting and lowering conduits when the opening of said hatchdoor is greater than said predetermined angle.

3. A device as claimed in claim 2, in which said kinematic coupling comprises a rocking-lever pivoted on the rod of the slide-valve of said hatchdoor distributor, a cam actuated by the undercarriage, a lever actuated by said cam and imposing, on one extremity of said rocking-lever, two positions depending on whether the undercarriage is in the down position or not, and a lever, actuated by the locking of the undercarriage in its retracted position, and imposing two positions on the other extremity of said rockinglever, depending on whether the undercarriage is in the locked and retracted position or not.

a ta e 

1. A control device for a retractable undercarriage and for the hatchdoor closing its housing, with their actuation and locking devices and control members for supplying said devices in mechanical-hydraulic sequences from a general conduit for lifting the undercarriage and a general conduit for lowering said undercarriage, comprising a jack for actuating said hatchdoor, a slide-valve distributor for supplying said jack and a kinematic coupling actuated mechanically by said undercarriage and placing said slide-valve in three characteristic positions: a first position controlled by the undercarriage in the lowered position and locked, in which said distributor causes the general lowering conduit to be in communication with the chambers of said jack actuating the closure of said hatchdoor, and said general lifting conduit with the chamber of said jack actuating the opening of said hatchdoor; a second position, controlled by the undercarriage in the unlocked position, in which said distributor acts, through the intermediary of passages of reduced section and spring clappervalves, to cause that of said two general lowering and lifting conduits which is under pressure to communicate with the chamber of said jack actuating the opening of said hatchdoor, and the other said general conduit to communicate with the chamber of said jack actuating the closure of said hatchdoor; a third position, controlled by the undercarriage in the retracted and locked position, in which said distributor causes said general lifting conduit to communicate with the chamber of said jack actuating the closure of said hatchdoor, and puts said general lowering conduit into communication with the chamber of said jack actuating the opening of said hatchdoor, said hatchdoor distributor comprising a first coupling connected to the general lifting conduit, a first orifice connected to said first coupling and opening into the bore of said distributor directly at its center, a first channel of reduced section connected to said first coupling, a first return clapper-valve connected to said first channel, a second orifice connected to said first valve and opening into the bore of said distributor on one side of its center, a second channel of reduced section connected to said first coupling, a second inlet clapper-valve connected to said second channel, a third orifice connected to said second valve and opening into the bore of said distributor on the other side of its center, a second coupling connected to said general lowering conduit, a third channel of reduced section connected to said second coupling, a third return clapper-valve connected to said third channel, a fourth oriFice connected to said third valve and opening into the bore of said distributor at the side of and beyond said second orifice, a fourth channel of reduced section connected to said second coupling, a fourth inlet clapper-valve connected to said fourth channel, a fifth orifice connected to said fourth valve and opening into the bore of said distributor at the side of and beyond said third orifice, a sixth orifice connected to said second coupling and opening into the bore of said distributor at the side of and beyond said fourth orifice, a seventh orifice connected to said second coupling and opening into the bore of said distributor at the side and beyond said fifth orifice, a third coupling connected to the chamber of said jack actuating the closure of said hatchdoor and opening into the bore of said distributor between said second and fourth orifices, a fourth coupling connected to the chamber of said jack actuating the opening of said hatchdoor and opening into the bore of said distributor between said third and fifth orifices, the slide-valve of said distributor being provided with two annular grooves, a first groove being able to put said second coupling into communication with two contiguous orifices of said first, second, fourth and sixth orifices, a second groove being able to put said fourth coupling into communication with two contiguous orifices of said first, third, fifth and seventh orifices.
 2. A device as claimed in claim 1, comprising a jack actuating the undercarriage, a distributor controlled by said hatchdoor and supplying said undercarriage jack only when the opening of said hatchdoor is greater than a predetermined angle, and a cam actuated by said hatchdoor and actuating said undercarriage distributor, said undercarriage distributor connecting the two supply conduits of said undercarriage jack to the general return conduit when the opening of said hatchdoor is less than said predetermined angle or to the general lifting and lowering conduits when the opening of said hatchdoor is greater than said predetermined angle.
 3. A device as claimed in claim 2, in which said kinematic coupling comprises a rocking-lever pivoted on the rod of the slide-valve of said hatchdoor distributor, a cam actuated by the undercarriage, a lever actuated by said cam and imposing, on one extremity of said rocking-lever, two positions depending on whether the undercarriage is in the down position or not, and a lever, actuated by the locking of the undercarriage in its retracted position, and imposing two positions on the other extremity of said rocking-lever, depending on whether the undercarriage is in the locked and retracted position or not. 